1. Field
The present disclosure relates to catheter based systems used to deliver medical devices.
2. Discussion of the Related Art
Various medical devices require catheter based delivery systems. Such medical devices include implantable, diagnostic and therapeutic devices. Common implantable, endovascular devices can include stents, stent grafts, filters, occluders, sensors and other devices. Endovascular devices are commonly advanced through the native vasculature to a treatment site by the use of a flexible catheter. When properly positioned at the treatment site the device (in the case of a stent) can be expanded to appose the vasculature. The device can then be released from the catheter allowing the catheter to be withdrawn from the vasculature. It is desirable to pre-compact endovascular devices into small delivery profiles in order to minimize vascular trauma and enhance maneuverability through torturous anatomies. A highly compacted device is often relatively stiff and is therefore difficult to bend into a small radius. A soft, flexible “olive” or tip is commonly positioned distal to the compacted device at the leading end of the delivery catheter, again to minimize vascular trauma and to enhance the positioning accuracy. As the device is advanced through a curved vessel, the junction between the relatively stiff compacted device and the soft flexible tip can “open up” presenting a gap.
To minimize this gap between a semi-rigid compacted device and a soft flexible leading tip various gap fillers and covers have been suggested. For example, a rigid catheter can be used to constrain a device into a small profile. The rigid catheter can extend distally beyond the device and over a portion of a leading tip, therefore covering a potential gap. The device can be allowed to expand by retracting the rigid catheter.
It remains desirable to have a device delivery system incorporating a releasable sleeve constraint along with an effective means to cover any potential undesirable gap between the compacted device and a leading catheter tip.